OSLO - The Norwegian government on Tuesday proposed opening its waters to deep-sea mining despite opposition from green campaigners and some countries, as it seeks to shift from a reliance on hydrocarbons to new sources of economic activity.

Norway, whose vast oil and gas reserves made it one of the world's wealthiest countries, has taken a leading role in the global race to mine the ocean floor for metals that are in high demand as countries transition away from fossil fuels.

"We need minerals to succeed with the green transition," Oil and Energy Minister Terje Aasland said in a statement.

The areas to be opened are in the Greenland Sea, the Norwegian Sea and the Barents Sea and cover an area of some 280 000 square kilometres (108 000 square miles), slightly smaller than the United Kingdom and Ireland put together.

From that total surface, licenses for smaller areas would be offered to exploration companies over time.

The move is controversial with conservationists, who warn that mining the ocean floor would threaten the biodiversity of vital ecosystems.

France in January banned deep-sea mining in its waters, while Germany has called for a pause in the development of the industry.

"This is a new low from the Norwegian government. They are continuing exploration for oil in the fragile Arctic and now opening up vast ocean areas for mining companies," Frode Pleym, head of Greenpeace Norway, told Reuters.

"Norway presents itself as green on the global scene but their actions say otherwise."

The government has said it would open the areas responsibly.

A Norwegian study said in January it had found a "substantial" amount metals and minerals, ranging from copper to rare earth metals, including an estimated 38 million tonnes of copper, almost twice the volume mined globally each year.

Parliament is set to debate the proposal in the autumn. The centre-left coalition rules in a minority but the proposal could pass with the support of some opposition parties.

The largest one, the Conservatives, who initiated the process when they were in power, said it would "carefully consider" it.